This invention relates generally to counterbalance spring assemblies for use on heavy doors mounted to swing between open, overhead positions and closed positions, and more particularly to such assemblies adapted for use on two-car garage doors with substantially no risk of spring breakage, or damage or injury from broken spring fragments in the unlikely event of such breakage.
Many homes today have double garages with heavy, spring-loaded doors adapted to swing between horizontal overhead (open) positions and vertical (closed) positions. Such a door is typically counterbalanced with tension springs so mounted as to come under high stretching tension when the door is closed and to help pull the door to its open position after it has been moved partly in that direction from a closed position by an outward pull on a handle on the bottom half of its outer side. These springs often break when the garage door is closed and they are under tension. At times in the past when this has occurred, metal spring fragments have been released with great force to damage whatever they struck. There have even been instances of grave injury to persons who have been struck by such fragments. While past attempts have been made to minimize the dangers inherent in such spring assemblies, none has been entirely successful. In this connection, some jurisdictions now require that spiral tension springs sold for use in such assemblies be equipped with internal safety wires, or the like, intended to prevent the flying escape of most spring fragments in the event of spring breakage. The presence of such wires does not necessarily prevent the release of all spring fragments, however. U.S. Pat. No. 3,402,922, which was granted to Henry F. McCan in 1968, discloses a telescoping shield adapted for installation around conventional garage door counterbalance springs, but no such product is available on the market insofar as I am aware.
In addition to the safety hazard inherent in the conventional garage door spring assemblies referred to above, such assemblies have other disadvantages. Thus, when a spring breaks it is virtually impossible for even a strong man to open the affected door without additional help. When the door is finally opened, generally by the brute strength of at least two men, it must be propped open while the broken spring is replaced. The replacement of the spring, itself, is difficult, and, in fact, impossible for the average woman and many men to accomplish. Where pairs of springs are employed, as they generally are, and both springs of a pair break, this compounds the difficulty of opening the door and repairing the spring assembly. If the garage door is not adequately supported in its open position while the spring assembly is undergoing repair, it can slip away from its support and close with enough force to severely injure or even kill anyone close-by who does not move out of the way fast enough.
In short, conventional spring-mounted garage doors of the above-described type pose an ever present risk of damage to property and injury to persons as a result of spring breakage, which can occur without warning at any time. Additionally, such breakage can cause great inconvenience and create an additional risk of injury from the unbalanced door while repair work is going on.